Originally used in reference to people imitating the fashion or style of cowboys. These people wore the hats, but had no experience on the ranch -- thus, all hat, no cattle. Similar to talking the talk without walking the walk (which was originally used in reference to wanabe gunslingers).
Roger says he's a great cook, but he sliced his thumb off trying to peel a potato. He's all hat, no cattle.
by Al September 28, 2006